1. Field of the Invention
The field of the invention relates generally to antennas.
2. Background Art
To produce a circularly polarized antenna, conventional approaches produce two orthogonal linearly polarized electric field components by providing two feeds to the antenna. The two feeds excite two orthogonal (e.g., X direction, Y direction) electromagnetic field modes such that one of the modes is excited with a 90 degrees phase delay relative to the other mode. Circular polarization (CP) may also be achieved using a single feed by placing the feed along one of the diagonals in a square patch, by including thin diagonal slots in a square patch, by elliptical patch shapes, or by trimming opposite corners in a square patch.
In certain conditions, conventional methods for producing CP may be inadequate. In addition, there is a need that the antenna system be re-configurable to produce as many types of polarizations as possible, to increase its utility.
The present disclosure will be described with reference to the accompanying drawings. Generally, the drawing in which an element first appears is typically indicated by the leftmost digit(s) in the corresponding reference number.